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5,6-Dihydropteridine reductase

FIGURE 40-2 The phenylalanine hydroxylase (PAH) pathway. Phenylketonuria usually is caused by a congenital deficiency of PAH (reaction 1), but it also can result from defects in the metabolism of biopterin, which is a cofactor for the hydroxylase. Enzymes (1) Phenylalanine hydroxylase (2) Dihydropteridine reductase (3) GTP cyclohydrolase (4) 6-pyruvoyltetrahydrobiopterin synthase. BH4, tetrahydrobiopterin DEDT, o-erythro-dihydroneopterin triphosphate QH2, dihydrobiopterin. [Pg.672]

Rarely, phenylketonuria results from a defect in the metabolism of biopterin, a cofactor for the phenylalanine hydroxylase pathway. The electron donor for phenylalanine hydroxylase is tetrahydrobiopterin (BH4), which transfers electrons to molecular oxygen to form tyrosine and dihydrobiopterin (QH2 Fig. 40-2 reaction 2). BH4 is regenerated from QH2 in an NADH-dependent reaction that is catalyzed by dihydropteridine reductase (DHPR), which is widely distributed. In the brain, this... [Pg.673]

DHPR dihydropteridine reductase GIRK G-protein-coupled inwardly rectifying K+ channel... [Pg.964]

K., Wachter, H., Werner-Felmayer, G., Mayer, B., Identification of the 4-amino analogue of tetrahydrobiopterin as a dihydropteridine reductase inhibitor and a potent pteridine antagonist of rat neuronal nitric oxide synthase, Biochem. J. 320 (1996), p. 193-196... [Pg.279]

DIHYDROOROTATE DEHYDROGENASE DIHYDROOROTATE OXIDASE DIHYDROPTERIDINE REDUCTASE DIHYDROPTEROATE SYNTHASE DIHYDROPYRIMIDINASE DIHYDROURACIL DEHYDROGENASE Dihydroxyacetone kinase,... [Pg.737]

BH4 is essential for the AAHs to carry out their respective catalytic reactions and, at least for PAH, the prereductive activation, which appears to produce dihydrobiopterin quinonoid (g-BH2) directly (20). After the PAH catalytic cycle an oxygen atom is incorporated into the cofactor, providing 4a-OH-BH4 which dissociates from the active site. In order to regenerate the functional tetrahydro form of BH4 pterin carbinolamine dehydratase catalyzes the dehydration of 4-OH-BH4 to g-BH2, which is reduced back to by dihydropteridine reductase (Scheme 2). g-BH2 can also be converted to 7,8-dihydropterin (BH2) which can be regenerated to BH4 by dihydrofolate reductase (DHFR). [Pg.447]

Important for the validity of the models that we constructed is the evidence from models of other proteins indicating that two proteins can have as little as 20 to 25% sequence identity and still have very similar 3D structures, especially in a helices and [3 stands [49-52]. Variation is found in the loops and coiled structures. A relevant example for this chapter is the comparison of the tertiary structure of rat dihydropteridine reductase [33] and Streptomyces hydrogenans 20(3-hydroxysteroid dehydrogenase [34]. As noted by Varughese et al. [33], despite less than 20% sequence identity between dihydropteridine reductase and... [Pg.197]

Varughese KI, Xuong NH, Kiefer PM, Matthews DA, Whiteley JM. Structural and mechanistic characteristics of dihydropteridine reductase a member of the Tyr- (Xaa)3-Lys-containing family of reductases and dehydrogenases, proc Natl Acad Sci USA 91 1994 5582-5586. [Pg.209]

A Fig. 6.1.7a- HPLC of pterins using a column-switching system a standard mixture b control urine c urine guanosine triphosphate cyclohydrolase I (GTPCH) deficiency d urine 6-pyru-voyl-tetrahydropterin synthase (PTPS) deficiency e urine pterin-4a-carbinolamine dehydratase (PCD) deficiency f urine dihydropteridine reductase (DHPR) deficiency g urine phenylketonuria 4-8 h after tetrahydrobiopterin (BH4) administration h-k see next page... [Pg.679]

DHPR Dihydropteridine reductase, DRD dopa-responsive dystonia, GTPCH GTP cyclohydrolase I, n normal, PCD pterin-4a-carbinolamine dehydratase, PTPS 6-pyruvoyltetrahydrobiopterin synthase, SR sepiapterin... [Pg.685]

Milstien S, Holtzman NA, Flynn ME, Thomas GH, Butler IJ, Kaufman S (1976) Hyper-phenylalaninemia due to dihydropteridine reductase deficiency. Assay of the enzyme in fibroblasts from affected infants, heterozygotes, and in normal amniotic fluid cells. J Pediatr 89 763-766... [Pg.702]

Arai N, Narisawa K, Hayakawa H, Tada (1982) Hyperphenylalaninemia due to dihydropteridine reductase deficiency diagnosis by enzyme assays on dried blood spots. Pediatrics 70 426-430... [Pg.702]

Narisawa K, Arai N, Hayakawa H, Tada (1981) Diagnosis of dihydropteridine reductase deficiency by erythrocyte enzyme assay. Pediatrics 68 591-592... [Pg.702]

Hyland K, Heales SJ. (1993) Tetrahydrobiopterin and quinonoid dihydrobiopterin concentrations in CSF from patients with dihydropteridine reductase deficiency. J Inherit Metab Dis 16 608-610... [Pg.702]

CFD is further associated with the following inherited metabolic disorders 5,10-methylen-tetrahydrofolate reductase (MTHFR) deficiency [7], 3-phos-phoglycerate dehydrogenase (PGDH) deficiency [8], dihydropteridine reductase (DHPR) deficiency [9], as well as with Rett syndrome [10], and Aicardi-Gou res Syndrome [11]. Furthermore, folate deficiency may be associated with congenital folate malabsorption, severe malnutrition, and formiminotransferase deficiency. [Pg.717]

Dihydropteridine reductase (from sheep liver) M 52,000 [EC 1.6.99.7]. Purified by fractionation with ammonium sulphate, dialysed versus tris buffer, adsorbed and eluted from hydroxylapatite gel. Then run through a DEAE-cellulose column and also subjected to Sephadex G-lOO filtration. [Craine et al. JBC 247 6082 7972]. [Pg.479]

Dihydropteridine reductase (from human liver) M 52,000 [EC 1.6.99.7]. Purified to homogeneity on a naphthoquinone affinity adsorbent, followed by DEAE-Sephadex and CM-Sephadex chromatography. [Firgaira, Cotton and Danks, BJ 197 31 7957]. [For other dihydropteridine reductases see Armarego et al. Medicinal Research Reviews 4(3) 267 7954]. [Pg.479]

Figure 10.10. Role of tetrahydrobiopterin in aromatic amino acid hydroxylases. Phenylalanine hydroxylase, EC 1.14.16.1 tyrosine hydroxylase, EC 1.14.16.2 tryptophan hydroxylase, EC 1.14.16.4 and dihydrobiopterin reductase (dihydropteridine reductase), EC 1.6.99.7. Figure 10.10. Role of tetrahydrobiopterin in aromatic amino acid hydroxylases. Phenylalanine hydroxylase, EC 1.14.16.1 tyrosine hydroxylase, EC 1.14.16.2 tryptophan hydroxylase, EC 1.14.16.4 and dihydrobiopterin reductase (dihydropteridine reductase), EC 1.6.99.7.
The reductant here is tetrahydrohiopterin, an electron carrier that has not been previously discussed and is derived from the cofactor biopterin. Because biopterin is synthesized in the body, it is not a vitamin. Tetrahydrohiopterin is initially formed by the reduction of dihydrobiopterin by NADPH in a reaction catalyzed by dihydrofolate reductase (Figure 23.28). NADH reduces the quinonoid form of dihydrobiopterin produced in the hydroxylation of phenylalanine back to tetrahydrohiopterin in a reaction catalyzed by dihydropteridine reductase. The sum of the reactions catalyzed by phenylalanine hydroxylase and dihydropteridine reductase is... [Pg.969]

Vol. 62 [57]. Antibodies that Bind Biotin and Inhibit Biotin-Containing Enzymes. M. Berger. Vol. 66 [102]. Preparation of an Antiserum to Sheep Liver Dihydropteridine Reductase. S. Milstein and S. Kaufman. [Pg.483]

Woody RC, Brewster MA. Adverse effects of trimethoprim-sulfamethoxazole in a child with dihydropteridine reductase deficiency. Dev Med Child Neurol 1990 32(7) 639 2. [Pg.3229]

Extrapyramidal symptoms developed with co-trimox-azole in a girl with dihydropteridine reductase deficiency and rapidly disappeared after withdrawal. This variant of phenylketonuria should be considered in all infants found to have raised phenylalanine concentrations during the neonatal period (46). [Pg.3511]

COS cells have been used for the production of recombinant proteins, including HSV-1 glycoprotein B, ricin B chain, placental alkaline phosphatase, thrombomodulin, CD7, von Willebrand factor, human dihydropteridine reductase, human P-glucuronidase, interleukin 5 and human interferon-... [Pg.6]


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Dihydropteridine reductase deficiency

Dihydropteridine reductase deficiency DHPR)

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